Compact 240W adapter reference design uses TO-220 GaN FETs

Compact 240W adapter reference design uses TO-220 GaN FETs

Technology News |
By Nick Flaherty

Transphorm has developed a reference design for a 240W AC-DC power adapter using through-hole TO-220 gallium nitride (GaN) transistors.

The TDAIO-TPH-ON-240W-RD design uses onsemi’s NCP1654 continuous current mode (CCM) boost power factor correction (PFC) combined with a NCP1399 half-bridge LLC controller.

The 24V 10A design uses three SuperGaN TP65H150G4PS FETs each with an on-resistance of 150 milliohms. The 3-lead TO-220 packages for the FETs provides improved thermal performance at lowline for higher current power systems running PFC configurations.

At the 180kHz switching frequency this gives a peak power efficiency of over 96 percent with a power density up to 30 W/in3 as a result of the FET packaging. Transphorm offers the only high voltage GaN devices in a TO-220 package today.

This allows higher currents at the lowline 90 Vac voltage rather than requiring two PQFN packages in parallel as typically seen with e-mode GaN transistors.

The reference design is intended to simplify and quicken power system development for applications such as high-power density AC-to-DC power supplies, fast chargers, IoT devices, laptops, medical power supplies, and power tools.


A 25mm heatsink allows a power density of over 24 W/in3 but can be increased by approximately 25 percent to 30 W/in3 depending on the heatsink design.

The new reference design joins five open frame USB-C PD reference designs ranging from 45 to 100 watts. It also includes two open frame USB-C PD/PPS reference designs for 65W and 140W adapters.

The TDAIO-TPH-ON-240W-RD design files are currently available for download at


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